June 28, 2012 -- The FDA has approved a new drug called Myrbetriq to treat overactive bladder.

Myrbetriq is an extended-release pill taken once a day. Overactive bladder is a condition in which the bladder muscle cannot be controlled, so it contracts at inappropriate times. Symptoms of overactive bladder include:

the need to urinate too often (urinary frequency)

inability to put off urination (urinary urgency)

involuntary urine leakage (urge incontinence)

In a news release, the FDA says Myrbetriq's safety and effectiveness were demonstrated in three studies that compared the drug to a placebo. The studies involved more than 4,000 patients.

"An estimated 33 million Americans suffer from overactive bladder, which is uncomfortable, disrupting, and potentially serious," Victoria Kusiak, MD, of the FDA's Center for Drug Evaluation and Research, says in the news release. "Today's approval provides a new treatment option for patients with this debilitating condition."

FDA Approval Was Anticipated

The drug's approval follows an FDA advisory panel vote in April that recommended approval. The recommendation was made even though concerns had been raised about an increase in blood pressure and liver issues in users.

Myrbetriq (mirabegron) is the first of a new class of drugs. It works by stimulating receptors in the bladder's detrusor muscle. This causes the bladder to relax, which reduces urinary urgency symptoms.

In the company-sponsored trials, conducted in the U.S. and Europe, people who took the drug had significantly fewer symptoms of urgency, urinary frequency, and urge incontinence than people who took placebo pills.

The drug was approved for sale in Japan last year and is marketed under the trade name Betanis.

'Clear Need for New Drugs'

Urologist Elizabeth Kavaler, MD, of Lenox Hill Hospital in New York City, says there is a clear need for new types of drugs that work in new ways to treat overactive bladder.

She says the previously approved prescription medications available in the U.S. all work in the same way.

"These drugs are very effective -- around 90% of patients who take them respond," she tells WebMD. "The problem is that many patients find they can't or don't want to take these drugs."

People with OAB can also reduce drinking all fluids and practice Kegel exercises to strengthen pelvic muscles.

If these lifestyle changes do not improve symptoms, medication may be needed, she says.

Kavaler says Myrbetriq may prove to be easier to tolerate for patients who either can't take the previously available drugs or who find the side effects intolerable.

"Clearly, we have a huge need in this area, as evidenced by the fact that so many companies are marketing what is essentially the same drug," she says. "It will be nice to have something different to offer."